UN_plot_hist: Histogram of a vector
In polgia0/Chemometricmenus: Chemometric package

Description Usage Arguments Details Value Author(s) Examples

Histogram plot of a vector

1	UN_plot_hist(previous.name = "")

previous.name

name of the default name in the menu

Vectorname of the vector dataset

The data distribution plays an important role in statistics; chemometrics is not so happy with this concept because the number of available data is often small and the type of distribution is often unknown. Actually, the value of a variable x (say the concentration of a chemical compound in a set of n samples) will have an Empirical Distribution; whenever possible the distribution of x should be visually inspected to obtain a better insight of the data. A number of different plots can be used for this purpose. The Histogram is the most frequently used graphic for frequency plots. Histograms allow easily to recognize the shape of the empirical distribution of x; however, outliers may cause problems. The first step in the construction of a histogram is the selection of the number of class intervals, also called classes, or bins, in which the data set values should be grouped. As regards the choice of the number of class intervals, several rules of thumb are applied such as for instance the square root of n. The subject however is not trivial, and the User is addressed to Reference books quoted or to R forum sites such as http://stackoverflow.com/, and http://www.statmethods.net/ or similar searching the keywords bin width or Number of bins.

A window plot

Riccardo Leardi and Gianmarco Polotti with contributions from Giorgio Marubini.Gruppo di Chemiometria (Divisione di Chimica Analitica della Societa' Chimica Italiana)